KEP-4049: Update KEP readme

[cupnes]

• One-line PR description: Update KEP readme to use the latest template and add explanation about this discussion.

• Issue link: Add storage capacity scoring #4049

• Other comments:

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[k8s-ci-robot]

Hi @cupnes. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[cupnes]

I will add a commit about this discussion once it reaches a conclusion.

[cupnes]

The update to the KEP readme is complete, so please review it.

Regarding commit 8c08201, we have not yet received a response from @jsafrane on the discussion about the revision approach on Slack. However, since the Enhancements Freeze on February 14th is approaching, I made the changes based on my proposed approach. If the outcome of the discussion changes, I will adjust the revisions accordingly.